Results: A catalyst made of iron, carbon, and nitrogen works nearly as well as platinum-based catalysts to accelerate the electrochemical reactions inside hydrogen fuel cells. The material produces 35 times as much current as previous catalysts not made of precious metals.

Why it matters: Hydrogen fuel cells for electric cars show promise because they emit no harmful pollutants, but they’ve been far too expensive to be practical. The new catalyst would greatly reduce the need for costly platinum in the fuel cells’ electrodes, making the technology cheaper.

Methods: The researchers improved the performance of a catalyst they had previously developed, in which nitrogen atoms and an iron ion bridge tiny gaps formed in a carbon material to create active sites for catalysis. To increase the number of these active sites, the researchers used a commercially available type of carbon that contains a large number of microscopic pores, which they packed with a material containing nitrogen and iron. When the material is heated under certain conditions, the nitrogen and iron arrange themselves into the catalytic bridges.

Next steps: To be practical, the catalyst needs to become more durable; in the researchers’ experiments, the reaction rates dropped by half after only 100 hours of testing. The reaction rates of the catalyst are also limited by how fast oxygen can move through the material to reach the active sites; this needs to be improved for the catalyst to work in fuel cells.